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Fakultät Elektrotechnik und Informationstechnik Institut für Halbleiter- und Mikrosystemtechnik

Fundamental insight into ALD processing by in-situ observationsitu observation

Johann W. BarthaM Alb t M J i d M K tM. Albert , M. Junige and M. Knaut

Grenoble 8 10 2013Grenoble, 8.10.2013

Introduction of TU Dresden Institute for Introduction of TU Dresden, Institute for Semiconductors and Microsystemsand ALD applications (@ TUD IHM)

1. Atomic Layer Deposition (ALD) basics

2. Tools and setups, parameters and complexity

3. Process development (Precursor qualification)

- approaches (ex-situ, in-situ, in-situ 1 Cycle)

QCM- QCM

- SE

4 S4. Summary

IHM = Institut für Halbleiter- und Mik h ikMikrosystemtechnik

Semiconductor TechnologyProf Bartha

HLTHLTHLTHLT

Postal address:TU Dresden - IHM

OESMST&

PMSOES

MST&

PMS

Optoelectronic Systems

Prof LaknerMicro Systems Technology

Prof FischerPolymeric Micro Systems

Prof Richter01062 Dresden

+49 351 463 35292Fax: +49 351 463 37172

PMSNEM

PMSNEM

http://www.ihm.tu-dresden.deNanoelectronic Materials

Prof Mikolajick

400 sqm cleanroom class 10/100/1000

ALD films as …… gate stacks on MOSFET/CNT/SiNW… Cu diffusion barriers… ECD seed layers (HAR TSV)

moisture barriers (OPV OLED)… moisture barriers (OPV, OLED)…

ALD of Ta-based Adhesion Layers for CNT-Cu Matrix Composite Film GrowthC. Hossbach et al, Proc. MSR Spring Meet., San Francisco (US), 2007

Atomic layer deposition for high aspect ratio through silicon viasKnaut et al., Microelectronic Engineering, Volume 107, July 2013, Pages 80-83

One ALD Application at IHM: 3D TSV Technology

Model of a 3D TSV Transfer line on an interposer2 µm Cu

900 nm SiO2

5 nm TaN15 nm Ru

20,4 µmµm

Process flow at IHM:- Si deep etching

Thermal oxidation

189

µm

- Thermal oxidation- Conformal barrier and seed layer by ALD- Conformal Cu ECD- Generation of redistribution - Bumping






QCM- QCM

- SE

4 Summary4. Summary

ATOMIC LAYER DEPOSITION

half-reaction A purge or evacuation

half reaction Bpurge or evacuation half-reaction Bpurge or evacuation

Self limiting growth behavior! Cyclic application!

ATOMIC LAYER DEPOSITION

half-reaction B purge or evacuation

half-reaction A purge or evacuation

ligand elimination, surface reactivation & film densification

metal-organic precursor adsorption (surface-controlled self-saturating & irreversible) & film densification

mou

nt

mou

nt

(surface controlled, self saturating & irreversible)

mou

nt

mou

nt

mat

eria

l am

mat

eria

l am

mat

eria

l am

mat

eria

l am

Ar purging timeexposure time of reactant B

Ar purging timeexposure timeof precursor A

V. Miikkulainen et al.: J. Appl. Phys. 113, 21301 (2013).

S. Elliott, and M. Shirazi: AVS 59th International Symposium & Exhibition (AVS, Tampa, 2012).






QCM- QCM

- SE

4 S4. Summary

Impact of Process Parameters GPC

Important parameters for ALD process development:

- Substrate temperature defined by substrate, precursor,

ALD windowapplication or desired film properties

- Precursor and reactant doses as low as possible to save time and money

temperature

ALD window

GPCbut as high as needed for saturation

- Sufficient purge times to avoid CVD as short as possible to save time

GPC

- Gas flow optimization and pressure effects tool and application

d d t

precursor dose

surface saturated

GPCGPCdependent affecting process

parameters

GPC

ffi i t

purge time

purge sufficient ALD behavior

purge time

ALD TOOLS at IHM

5 ALD tools

8 ALD chambers

Up to 300 mm wafer size

In-situ RTP, Flash Lamps, …

In-situ methods and equipmentq p

300 mm ALD cluster tool (FHR Anlagenbau)

Handler chamber and load lock

Reaction chambers with direct in-situ analytics real time in situ measurements real-time in-situ measurements QCM, QMS, SE highly sensitive non-invasive

Connected Omicron UHV analytics tool in-vacuo measurements XPS, UPS, AFM, STM extremely sensitive no vacuum break no contamination






QCM- QCM

- SE

4. Summary

Process Development GPC

(ex-situ film measurement)

temperature

ALD window

GPC

precursor dose

surface saturated

GPCGPC

Many Parameters

Folie 15 von 47purge sufficient ALD behavior

purge time

Many Parameters many deposition runs very time consuming!

Process developmentIn-situ using one sampleusing one cycleProcess development

film-thick-

Ex-situ method

In situ using one sample

film-thick-

In-situ 1-cycle method

using one cycle

ness ness

# of cycles time

GPCfilm-thick-ness

In-situ method

surface saturated ALD

Precursor Dose(Pulse time)# of cycles

Parameter

Quartz crystal microbalances - QCMQuartz crystal microbalances QCM

300 mm Cross-Flow Reactorwith heated chamber in chamberwith heated chamber in chamber

2 sensors (inlet + outlet)

Different crystal materials

≈V ∆f ≈ -∆m≈V ∆f ≈ -∆m

12“ wafer

P ibl h i i i l i f d d d lPossible approaches using in-situ analytics for advanced process development …

1. Approach - Automated precursor testing with short sub-processespp p g p

Comparable to standard process development with short sub-processes

but without wafer or sample loading/unloading, heat up, additional

measurement steps

Same data like using ex-situ measurements

Easy data acquisition and evaluation Easy data acquisition and evaluation

Higher reliability

P ibl h i i i l i f d d d lPossible approaches using in-situ analytics for advanced process development …

2. Approach - Analysis and comparison of single ALD cyclespp y p g y

pulse times for saturation impact extractable from every cycle

correlation between parameters and film growth mechanisms

evaluation more complex

prone to errors (drifts, noise, …)

fundamental understanding

TMA purge H2O purge

fundamental understanding

very fast method

1. Approach: 10 cycles per parameter set 2. Approach: Monitoring of single cycles

Growth per cycle TTIP adsorption

Fundamental insights: growth mechanisms and parameter impact on surface reactions

TiO2 ALD

from TTIP and H2O

1. TTIP chemisorption

2. Ar purging

3 i d l b O3. Ligand removal by H2O

4. Ar purging

1st half-reaction:

Process pressure affects

amount of chemisorbed TTIP

2nd half-reaction:

No process pressure p p

impact on ligand removal

In situ monitoring allows to understand non-uniformity issues by

comparing single ALD cycles at two QCM sensor positions

outlet

Outlet QCM sensor shows delayed film growth for higher process pressures

(triggered by inlet QCM sensor)

Reduced speed of process gasses Reduced speed of process gasses

Process development – applying Spectroscopic Ellipsometry

Measurement on the substrate!

M. Junige et al.: IEEE Semiconductor Conference Dresden(Dresden, 2011).

PROCESS PARAMETER (INTER)DEPENDENCIES

growth per cycle (Å/cycle)

1 0

Ru film thickness (nm)

successive sub-processes

0,0

0,5

1,0

ECPR pulsing (s)

0 5 10 15

0,5

1,0

0,0

0,5

0 5 10 15 20

O2 pulsing (s)

1 0

ALD cycle number0,0

0,5

1,0

deposition temperature

(°C)

ALD cycle number

M. Knaut et al.: J. Vac. Sci. Technol. A 30, 01A151 (2012).

M. Junige et al.: IEEE 2011 Semiconductor Conference Dresden (IEEE, Dresden, 2011).

150 250 350

irtSE: TA2O5 ALD (PULSEWISE RESOLUTION)

Ta2O5 optical layer thickness

in progression of 100 ALD cycles in the course of one ALD cycle

3,0

3,5

s (Å

)

1,5

2,0

2,5

ayer

thic

knes

s

TB

TE

MT

O3

0,5

1,0

optic

al la

0,00 60 120

time (s)

growth per cycle ≈ 0.6 Å at an actual deposition temperature of 215 °C

M. Junige et al.: DPG-Frühjahrstagung (DPG, Dresden, 2014).

irtSE: AL2O3 ALD (PULSEWISE RESOLUTION)

3 3

averaged optical layer thickness in the course of one Al2O3 ALD cycle at varied substrate set-point temperatures

3

ss (Å

)

500 °C400 °C300 °C

2

3

ss c

hang

e (Å

)

2

yer

thic

knes 200 °C

100 °C TMA0

1

3 4 5 6 7 8 9

thic

knes

time (s)

MA

1

optic

al la

y

-1

0

chan

ge (Å

)

( )

TM

A

O3

00 60 120 180

time (s)

O3-2

70 80 90 100

thic

knes

s

time (s)time (s) time (s)

M. Junige et al.: 8th Workshop Ellipsometry (AKE, Dresden, 2014).

irtSE: AL2O3 ALD (PULSEWISE RESOLUTION)

thickness increment per Al2O3 ALD cycle (left) and pulsewise thickness changes (right)at varied deposition temperatures

32

1

2

3

ss c

hang

e (Å

)2

r cy

cle

(Å) cummulative over 100 ALD cycles

cyclewise by averaging last 10 of 100 ALD cycles

per TMA exposure0

1

100 200 300 400

thic

knes

actual Si surf. temp. (°C) 1

crem

ent p

er

p ( )

thic

knes

s inc

-1

0

s cha

nge

(Å)

per O3 exposure0100 200 300 400

t

actual Si surface temperature (°C)

-2100 200 300 400

thic

knes

s

actual Si surf temp (°C)

M. Junige et al.: 8th Workshop Ellipsometry (AKE, Dresden, 2014).

actual Si surface temperature ( C) actual Si surf. temp. (°C)

IN-VACUO XPS: AL2O3 ALD

carbon XPS signal (in vacuo) at varied substrate set-point temperatures

carbon contamination and Al-to-O ratio in dependence on the deposition temperature

550%

u.)

C 1s

4

5

40%

50%

(at.%

)

ratio

50:50

40:60

nten

sity

(a. u 100 °C

200 °C

2

3

20%

30%

tam

inat

ion

m-t

o-ox

ygen

20 80

30:70

XPS

in 300 °C

400 °C1

2

10%

20%

carb

on c

ont

alum

inum

10:90

20:80

280285290295300

binding energy (eV)

500 °C00%

0 100 200 300 400 500

actual Si surface temperature (°C)binding energy (eV)

V. Sharma: Student Research Project (Technische Universität Dresden, Dresden, 2014).

actual Si surface temperature ( C)

irtSE: TANX ALD (PULSEWISE RESOLUTION)

averaged optical layer thickness in the course of one TaNx ALD cycle (left) and resp. details (right) at varied substrate set-point temperatures

2

3

4

ss c

hang

e (Å

)

4

s (Å

)

TBTEMT0

1

3 8 13

thic

knes

time (s)2

3

yer

thic

knes

s

400 °C

300 °C

250 °C ( )

-1

0

chan

ge (Å

)

TE

MT

3

1

optic

al la

y 200 °C

175 °C

150 °C

120 °C

NH3-3

-2

60 70 80 90

thic

knes

s

time (s)

TB

T

NH

3

00 60 120

time (s)

120 °C

time (s)time (s)

M. Junige et al.: 12th International Baltic ALD conference (Helsinki, 2014).

irtSE: TANX ALD (PULSEWISE RESOLUTION)

4

(Å)

thickness increment per TaNx ALD cycle (left) and pulsewise thickness changes (right)at varied deposition temperatures

2

3

4

knes

s cha

nge

per TBTEMT exposure1

2

100 150 200 250 300

thic

k

actual Si surf temp (°C)

-1

0

ss c

hang

e (Å

) actual Si surf. temp. ( C)

per NH3 exposure-3

-2

100 150 200 250 300

thic

knes

100 150 200 250 300actual Si surf. temp. (°C)

M. Junige et al.: 12th International Baltic ALD conference (Helsinki, 2014).

IN-VACUO XPS: TANX ALD

Nitrogen content Carbon and Oxygen concentration






t t d t ti- automated testing

- advanced process development

4 S4. Summary

Summary

QCM and SE are capable to resolve

sub monolayer effectsy

This can be utilized to get information This can be utilized to get information

about the dynamics of the cycle

The GPC combines the effect of two

exposures and the dependency onexposures and the dependency on

process parameters need separately

to be understoodto be understood

Thank You!Spectroscopic Ellipsometer

Scanning Probe

Microscope

Quartz Crystal

Microbalance

X-ray / UVPhotoelectron Spectroscope pSpectroscope

XRD

4PP

QuadrupoleMass

Spectrometer

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Fundamental insight into ALD processing by in- situ ...semieurope.omnibooksonline.com/2014/semicon_europa/ALD/1... · Fundamental insight into ALD processing by in-situ observationsitu